The physical layer abstracts the higher architecture layers of the difficulties of interacting with the data sources. It also provides a vision of the data sources according to a common metamodel.
These tasks are carried out through the so-called wrappers. A wrapper extracts data from a source, interprets the results obtained and returns them to the system in the format required by Virtual DataPort metamodel. Furthermore, where permitted by the source, a wrapper can also insert, update and/or delete information in a source.
The wrappers allow Virtual DataPort to process all the external sources in a consistent manner, without concern for their specific characteristics. Virtual DataPort directly provides the following types of wrappers:
Relational database wrappers: they extract data from a Remote Database via JDBC or ODBC. Furthermore, where permitted by the source, a wrapper inserts, updates and/or deletes information in a source.
Multidimensional database wrappers: they extract data from multidimensional databases such as SAP BW, Mondrian, Oracle Essbase and Microsoft SQL Server Analysis Services.
Web services wrappers: they extract data invoking operations provided by SOAP Web services.
XML wrappers: they allow extracting data encapsulated in XML files. Those files can optionally be validated using a specific DTD or schema. XML documents can be accessed on the local drive or remotely accessed via protocols such as http or FTP. A common use of this type of wrapper is the importing of REST Web services (including RSS and ATOM web services).
Delimited files wrappers: they extract data from delimited files in CSV format (Comma Separated Values) or similar. CSV documents can be accessed on the local drive or on remote locations via HTTP or FTP.
Excel wrappers: they extract data from Microsoft Excel files. There are several configuration parameters that allow you to extract data from one or more worksheets, only from a certain range, etc.
Web wrappers: they provide access to semi-structured data contained in websites. For instance, these wrappers can automate the process of querying a web form and extracting the results. These wrappers are generated with Denodo ITPilot.
Aracne wrappers (deprecated): see section Denodo Aracne Wrappers.
LDAP wrappers: they extract data contained in LDAP directories such as Microsoft Windows Server Active Directory.
BAPI wrappers: they invoke SAP BAPIs (Business Application Programming Interfaces) to extract data stored in SAP ERP and other SAP applications.
Salesforce.com wrappers: they extract data from a Salesforce.com.
Custom wrappers: they extract data from a source through a Java implementation provided by the Virtual DataPort administrator. Virtual DataPort provides an API, so users can create their own wrappers for specific sources. The CUSTOM wrappers also allow inserting, updating and/or deleting data from the sources.
The Virtual DataPort Administration Tool creates all these wrappers automatically, except the Web (WWW) ones, which are created with the ITPilot Wrapper Generation Tool.